Apparatus for removing particles from a gaseous stream

ABSTRACT

Apparatus for removing particles from a gaseous stream is suitable either as a muffler for the exhaust of an internal combustion engine or as a filter for tobacco smoke and comprises a shaft, the outer surface of which defines at least one continuous helical groove. Two or more hollow tubes, each have a smooth inner surface and an outer surface defining at least one continuous helical groove. The shaft and the respective tubes are configured and dimensioned to be slidably received one within the other wherein the respective helical grooves constitute a plurality of concentric continuous helical conduits. The gaseous stream containing suspended particles is divided and directed simultaneously through the helical conduits wherein a large number of the particles are removed.

United States Patent [191 Steel Continuation of Ser. No. 157,503, June 28, 1971, abandoned. I

[76] inventor:

[52] US. Cl 55/435, 55/457, 60/311, 131/209, 131/217, 181/67 Int. Cl B01d 45/12 Field of Search l3l/209, 217; 181/66, 67; 60/311; 165/179, 184; 55/456, 457, 435,

References Cited UNITED STATES PATENTS 4/1922 Gruenmn, 131/217 11/1931 55/435 2/1939 60/311 4/1943 181/66 11/1967 Bergmann,

Parrigan 131/209 1 Apr. 23, 1974 FOREIGN PATENTS OR APPLICATIONS 804,593 8/1936 France 181/67 292,323 6/1928 Great Britain..,.. 181/67 [57] ABSTRACT Apparatus for removing particles from a gaseous stream is suitable either as a muffler for the exhaust of an internal combustion engine or as a filter for tobacco smoke and comprises a shaft, the outer surface of which defines at least one continuous helical groove. Two or more hollow tubes, each have a smooth inner surface and an outer surface defining at least one continuous helical groove. The shaft and the respective tubes are configured and dimensioned to be slidably received one within the other wherein the respective helical grooves constitute a plurality of concentric continuous helical conduits. The gaseous stream containing suspended particles is divided and directed simultaneously through the helical conduits wherein a large number of the particles are removed.

4 Claims, 3 Drawing Figures PATENTEDAPR 23 1914 i3 8 05 A95 INVENTOR. TO H N F. ST E E L Jam ATTORNEYS APPARATUS FOR REMOVING PARTICLES FROM A GASEOUS STREAM This is a continuation of application Ser. No. 157,503, filed June 28, 1971, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to gas filters and, more particularly to a novel filter suitable for use both as a muffler for the exhaust of an internal combustion engine and as a filter for any gaseous stream containing solid particles in suspension, especially tobacco smoke.

Automobile mufflers are well known in the prior art. Heretofore, the primary function of such mufflers has been to mute and to silence thesound produced by the rapid and continuous series of explosions which are produced during the operation of an internal combustion engine. This object usually has been accomplished by passing the exhaust gasses through and around a'series of baffles generally perpendicular to the direction of flow to diminish the noise resulting from the sharp pulses of expanding exhaust gasses. Mufflers in which the baffles are not perpendicular to the flow direction and in which the exhaust gasses are encouraged to follow a single swirling path are alsoknown (U.S. Pat. No. 2,274,599) as are mufflers which employ harmonics to deaden sound and in which the' gas'stream is divided but not diverted (U.S. Pat. No. 2,995,200). Although antipollution devices have been proposed for use in an internal combustion engine exhaust line in combination with a conventionalmuffler (U.S. Pat. No. 3,019,780), no muffler per se provides the anti-pollution feature of reducing the number of solid particles which are suspended in the exhaustgasses and areordinarily spewed into the atmosphere through countless tail pipes.

Filters for removing solid particles from a gaseous stream, particularly tobacco smoke, are also well known. Cigarette and cigar smoke filters are generally batts of cotton or paper through which smoke passes and in which solid particles suspended in the smoke become entrapped. Activated charcoal, waterimpregnated cotton and water alone have also been used to purify tobacco smoke. Some other attempts generally involve increasing the length and changing the directionof the path which the smoke must travel before being inhaled (U.S. 'Pat. Nos. 3,502,087 and 3,520,307) and one recent patent (U. S.- Pat. No. 3,525,345) employs two overlapping filter elements through which the smoke travels sequentially, each filter element including a spiral baffle which imparts a swirling motion to the smoke. None of these prior filters can be cleaned and reused and no such filter, divides the smoke stream and constrains the divided streams in predetermined paths without the interference of baffles or batts which make it more difficult to draw smoke without necessarily increasing the degree of filtration otherwise obtainable.

SUMMARY OF THE INVENTION The present apparatus for'removing particles from a gaseous stream comprises a solid elongated shaft including an outer surface defined by an upstanding strip smooth and complementary in cross-section to the outer surface of the shaft. The shaft is slidably and snugly received within the first tube and the helical groove of the shaft constitutes a first continuous helical conduit open only at either end of the shaft. The outer surface of the first tube is defined by an upstanding strip which extends substantially the entire length of the first tube and which is disposed in a plurality of spaced-apart helical turns to define a continuous helical groove. A second hollow elongated tube of about the same length as the first tube includes an inner surface and an outer surface. The inner surface of the second tube is substantially smooth and complementary in cross-section to the outer surface of the first tube. The first tube is slidably and snugly received within the second tube and the helical groove of the first tube constitutes a second continuous helical conduit, concentric with the first conduit and open only at either end of the first tube.'The outer surface of the second tube is de fined by an upstanding strip which extends substantially the entire length of the second tube and which is disposed in a plurality of spaced-apart helical turns to define a continuous helical groove. A hollow elongated tubular'sheath of about the same length as the second tube includes a substantially smooth inner surface which is complementary in cross-section to the outer surface of the second tube. The second tube is slidably and snugly received within the sheath and the helical groove of the second tube constitutes a third helical conduit, concentric with the first and second conduits and open only at either end of the second tube. A gaseous stream having particles suspended therein is divided and directed into and through the concentric conduits and is constrained within a plurality of helical pathways to remove a large number of the particles from the gaseous stream.

It is further contemplated that either fewer or additional complementary tubes may be employed and that the outer surfaces of each of the shaft and the tubes may be defined by at least two upstanding strips which are disposed in a plurality of spaced-apart helical turns to define at least two parallel continuous helical grooves. This latter construction, in particular, enables the provision of additional independent helical conduits further to divide the gaseous stream without either increasing the overall dimensions of the apparatus or decreasing the pitch of the conduits. Moreover, the present apparatus may either be disposed of after use or disassembled for cleaning and reuse depending upon the economic and other considerations of each particular end use; and, the groove surfaces may be either roughened or made of a material which readily retains the impinging particles in order to increase efficiency.

The present invention thus provides efficient removal of particles suspended in a gaseous stream by dividing and positively constraining the stream in a plurality predetermined paths wherein the particles are subject to centrifugal force and are impinged and retained upon the walls of conduits without undue back pressure which may increase substantially the energy required to pass the stream through the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in partial section of a cigarette holder including a filter cartridge which embodies the present apparatus;

FIG. 2 is a sectional view of the present apparatus progressively broken away to illustrate the structure and the interrelationshp of the respective components; and

FIG. 3 is a sectional view of a muffler for an internal combustion engine embodying the present apparatus which is progressively broken away to illustrate the structure and the interrelationship of the respective components.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown best in FIG. 2, apparatus for removing particles from a gaseous stream in accordance with the present invention comprises a solid elongated shaft 11 which includes an outer surface of essentially circular cross-section defined by upstanding strips l4, 15, respectively. In general, it is preferred that both the shaft 11 and other elements of the present apparatus 10 be essentially circular in cross-section, primarily because of convenience in manufacture. However, an oval or polygonal cross-section, for example, would suffice. The upstanding strips 14, 15 are disposed in a plurality of spaced-apart turns to define two continuous parallel helical grooves 16, 17. As shown in FIG. 2, groove 16 is defined by the space between adjacent turns of strip 14 on the left and strip 15 on the right whereas groove 17 is defined by the space between adjacent turns of strips 15 on the left and strip 14 on the right. defined by the space between A first hollow elongated tube 20 is about the same length as the shaft 11 and includes an inner surface and an outer surface, both of essentially circular crosssection. The inner surface of the first tube 20 is preferably substantially smooth and regular and is complementary in cross-section to the outer surface of the shaft 11. The shaft 11 is slidably and snugly received within the first tube 20 wherein the radially outermost portions of the strips 14, 15 abut the inner surface of the first tube 20. The helical grooves 16, 17 of the shaft 11 are thus completely enclosed and isolated from each other to constitute two independent continuous parallel helical conduits open only at either end of the shaft 11.

The outer surface of the-first tube 20 is essentially duits, concentric with the conduits of the shaft 11 and open only at either end of the first tube 20.

The outer surface of the second tube 30 is essentially circular in cross-section and is defined by upstanding strips 32, 33, respectively. The upstanding strips 32, 33 are disposed in a plurality of spaced-apart turns to define two continuous parallel helical grooves 35, 36. As shown in FIG. 2, groove 35 is defined by the space between adjacent turns of strip 32 on the left and strip 33 on the right while groove 36 is defined by the space between adjacent turns of strip 33 on the left and strip 32 on the right.

A hollow elongated tubular sheath is about the same length as the shaft 11 and the tubes 20, 30 and includes an inner surface of essentially circular crosssection. The inner surface of the sheath 40 is preferably substantially smooth and regular and is complementary in cross-section to the outer surface of the second tube 30. The second tube 30 is slidably and snugly received within the sheath 40 wherein the radially outermost portions of the strips 32, 33 abut the inner surface of the sheath 40. The helical grooves 35, 36 of the second tube 30 are thus completely enclosed and isolated from each other to constitute two independent continuous parallel helical conduits, concentric with the conduits of the shaft 11 and the first tube 20 and open only at either end of the second tube 30.

In operation, a gaseous stream having particles suspended therein is divided as it is directed simultaneously through the six helical conduits. The flow of the stream is unobstructed by baffles but is constrained circular 'in cross-section and is defined by upstanding 7 strips 22, 23, respectively. The upstanding strips 22, 23 are disposed in a plurality of spaced-apart turns to define two continuous parallel helical grooves 25, 26. As shown in FIG. 2, groove 25 is defined by the space between adjacent turns of strip 22 on the left and strip 23 on the right while groove 26 is defined by the space between adjacent turns of strip 23 on the left and strip 22 on the right.

A second hollow elongated tube 30 is about the same length as the shaft 11 and the first tube 20 and includes an inner surface and an outer surface, both of essentially circular cross-section. The inner surface of the second tube 30 is preferably substantially smooth and regular and is complementary in cross-section to the outer surface of the first tube 20. The first tube 20 is slidably and snugly received within the second tube 30 wherein the radially outermost portions of the strips 22, 23 abut the inner surface of the second tube 30. The helical grooves 25, 26 of the first tube 20 are thus completely enclosed and isolated from each other to constitute two independent continuous parallel helical conin a plurality of unobstructed helical pathways wherein centrifugal force aids in causing the heavier particles to be removed from the stream and deposited on the conduit walls. By dividing the gaseous stream into at least several parts, a maximum conduit surface area upon which the particles may impinge is obtained. In this regard, the number of conduits may be varied in accordance with the requirements of the particular contemplated end use. For example, the outer surfaces of each of the shaft 11 and the tubes 20, 30 may be provided with only a single helical strip rather than two such strips to obtain a single conduit for each such element or they may include three or morestrips to obtain a like number of conduits. Likewise, the number of tubes may be increased or decreased as may be required to achieve the desired degree of filtration. The efficiency of the apparatus 10 may be further increased by rough ening the surface of the respective helical grooves in order that suspended particles may adhere to the conduit walls more easily and in greater number.

It is further contemplated that the present apparatus 10 may be constructed either of metal such as steel, or aluminum or of a suitable resinous plastic where temperature conditions permit, and that the apparatus 10 be either disposable or reusable depending upon economic and other practical considerations. In the latter instance, the apparatus 10 may be disassembled quickly and easily for cleaning by slidably removing the shaft 11 from the first tube 20, the first tube 20 from within the second tube 30, and the second tube 30 from within the sheath 40 to expose completely all of the helical grooves. Although preferably the inside surfaces of the tubes 20, 30 and the sheath .40 are substantially smooth and regular to permit assembly and disassembly of the apparatus 10 by slidably engaging or disengaging the respective elements 11, 20, 30, 40 as previously described, it is further contemplated that theinside surfaces of the tubes 20, 30 and the sheath 40 may be provided with upstanding strips to define grooves which are complementary to but shallower than the grooves in the outer surfaces of adjacent elements. In this manner, the apparatus would be assembled or disassembhed by twisting or screwing the adjacent elements rather than by sliding them. Although the respective elements could be maintained in place more positively in this manner, the cross-sectional area of the helical conduits would be diminished to the extent that the strip of an inner surface of one element would extend into the grooves in the outer surface of the subjacent element, the processes of assembly, disassembly and cleaning would be made more difficult, and the manufacturing costs would necessarily be increased.

The present apparatus 10 is eminently suitable for use as a tobacco smoke filter. Referring particularly to FIG. 1, a standard cigarette or cigar holder 50 contains a cartridge which embodies the apparatus 10 of the present invention. A cigarette or cigar is inserted into an entrance opening 51 of the holder 50, lit, and the smoke is drawn into and through the apparatus 10 for filtration before passing through a mouthpiece exit 52. The cartridge may either be disposable or permanent and reusable as previously described. The present apparatus 10 may also be incorporated in the filter tip of a cigarette, in which case it would necessarily be disposable.

FIG. 3 illustrates a muffler for an internal combustion engine which embodies the present apparatus 10.

Adapters 60, 61 are secured to either end of the sheath in fluid-tight relationship. Each adapter 60, 61 has an opening 62, 63, respectively, and anannular fitting 64, 65, respectively which enable gas-carrying conduits to be secured to the muffler. It is further contemplated that the shaft 11 and tubes 20, 30 may be made ofa relatively inexpensive heat-resistant material to constitute a cartridge which may be replaced periodically in the same manner as an oil filter.

I claim:

1. A filter for removing particles from a gaseous stream comprising, a solid elongated shaft including at least two outer surfaces each being defined by an upstanding strip extending substantially the entire length of the shaft and disposed in a plurality of spaced apart helical turns to define at least two continuous helical grooves; a first hollow elongated tube of' about the same length as the shaft and including an inner surface and an outer surface, the inner surface of the first tube being substantially smooth and complementary in cross-section to the outer surface of the shaft, the shaft being slideably and snugly received within the first tube and the helical grooves of the shaft constituting a first continuous helical conduit, the outer surface of the first tube being defined by at least two upstanding strips extending substantially the entire length of the first tube and disposed in a plurality of spaced apart helical turns to define continuous helical grooves; a second hollow elongated tube of about the same length as the first tube and including an inner surface and an outer surface, the inner surface of the second tube being substantially smooth and complementary in cross-section to the outer surface of the first tube, the first tube being slideably and snugly received within the second tube and the helical grooves of the first tube constituting a second continuous helical conduit concentric with the first conduit, the outer surface of the second tube being defined by at least two upstanding strips extending substantially the entire length of the second tube and disposed in a plurality of spaced apart helical turns to define at least two continuous helical grooves; a hollow elongated tubular sheath of about the same length as the second tube and including an inner surface, the inner surface of the sheath being substantially smooth and complementary to the cross-section of the outer surface of the second tube, the second tube being slideably and snugly received within the sheath and the helical grooves of the second tube constituting a third plurality of continuous helical conduits concentric with the first and second conduits, wherein the respective surfaces of each helical groove of the shaft and tubes are roughened and wherein the shaft is slideably removable from within the first tube, the first tube is slideably removable from within the second tube and the second tube is slideably removable within the sheath wherein a gaseous stream having particles suspended therein is divided and directed simultaneously into and through the concentric conduits and is constrained within a plurality of helical pathways to remove by centrifugal force a large number of the particles from the gaseous stream.

2. Apparatus according to claim 1 wherein the shaft, the first and second tubes, and the sheath are metallic.

3. The apparatus according to claim 1 wherein the shaft, the first and second tubes, and the sheath are of tially circular in cross-section. 

1. A filter for removing particles from a gaseous stream comprising, a solid elongated shaft including at least two outer surfaces each being defined by an upstanding strip extending substantially the entire length of the shaft and disposed in a plurality of spaced apart helical turns to define at least two continuous helical grooves; a first hollow elongated tube of about the same length as the shaft and including an inner surface and an outer surface, the inner surface of the first tube being substantially smooth and complementary in cross-section to the outer surface of the shaft, the shaft being slideably and snugly received within the first tube and the helical grooves of the shaft constituting a first continuous helical conduit, the outer surface of the first tube being defined by at least two upstanding strips extending substantially the entire length of the first tube and disposed in a plurality of spaced apart helical turns to define continuous helical grooves; a second hollow elongated tube of about the same length as the first tube and including an inner surface and an outer surface, the inner surface of the second tube being substantially smooth and complementary in cross-section to the outer surface of the first tube, the first tube being slideably and snugly received within the second tube and the helical grooves of the first tube constituting a second continuous helical conduit concentric with the first conduit, the outer surface of the second tube being defined by at least two upstanding strips extending substantially the entire length of the second tube and disposed in a plurality of spaced apart helical turns to define at least two continuous helical grooves; a hollow elongated tubular sheath of about the same length as the second tube and including an inner surface, the inner surface of the sheath being substantially smooth and complementary to the cross-section of the outer surface of the second tube, the second tube being slideably and snugly received within the sheath and the helical grooves of the second tube constituting a third plurality of continuous helical conduits concentric with the first and second conduits, wherein the respective surfaces of each helical groove of the shaft and tubes are roughened and wherein the shaft is slideably removable from within the first tube, the first tube is slideably removable from within the second tube and the second tube is slideably removable within the sheath wherein a gaseous stream having particles suspended therein is divided and directed simultaneously into and through the concentric conduits and is constrained within a plurality of helical pathways to remove by centrifugal force a large number of the particles from the gaseous stream.
 2. Apparatus according to claim 1 wherein the shaft, the first and second tubes, and the sheath are metallic.
 3. The apparatus according to claim 1 wherein the shaft, the first and second tubes, and the sheath are of resinous plastic material.
 4. Apparatus according to claim 1 wherein the shaft, the first and second tubes, and the sheath are essentially circular in cross-section. 